Method of producing selenium disks for rectifiers and photoelectric cells



p 1 I H. HERRMANN' 2,213,279

,METHOD OF PRODUCING SELEN IUM DISKS FOR RECTIFIERS AND PHOTOELECTRIC CELLS Filed April 29. 1939 Patented Sept. 3, 1940 "PATENT. OFFICE;

METHOD or PRODUCING SELENIUM DISKS FOR RECTIFIERS AND rno'roELEoTaIc CELLS Heinrich Herrmann, Nuremberg, Germany, as-

signor to Siiddeutsche Apparate-Fabrik G. m. b. 11., Nuremberg, Germany, a company Application April 29, 1939, Serial No. 270,774

Germany May 4, 1938 1 Claim. (01. its-see) The invention relates to dry rectiflers and. photoelectric cells of the kind having a base plate coated with a. selenium layer on which-a disk-- shaped electrode is arranged. This' electrode is,

made to be imperviousto light if the selenium layer is to act as a rectifying means, but is lightpermeable if the selenium layer is to be used for photoelectric purposes. When manufacturing vsuch selenium disks, in order always to produce 0 a predetermined thickness thereof, namely, the

thickness best adapted for the purpose, the prac-i' tice has been to use a measuring spoon with the aid of which the selenium powder is applied to the base plate to form heaps thereon after this plate has been heated to some 300 degrees centigrade. Such heaps are then spread out on the base plate by means of a glass rod so as to form a coating on it. According to thearea oi the plate so coated with the selenium layer a greater or smaller number of selenium heaps have been applied in this way to the base plate, the contents of such measuring spoon being used up each time for forming a heap. v

As the selenium if employed in larger quantity is easier to'spread out on the base plate than with smaller quantities thereof the danger exists that more of the selenium is applied to the plate than is necessary for the desired thickness 0! the selenium layer. If, however, the selenium layer is too thick the losses in the'rectifler or photo'- electric cell are increased.

The difiiculty which thus arises in the manuiacture of the selenium disks is avoided by the invention. In accordance with the invention the se lenium is not employed in its powdery condition but is used in the form of tablets. The known tabletting machines enable the manufacture of selenium tablets which contain a precisely predetermined quantity of selenium. By tablettin the quantity of selenium to be applied this can 5 be' properly dosed, the application of the proper quantity thereof thus being easy to supervise in the course of manufacture. For instance, the addition of one tablet'beyond the prescribed number will be easy to perceive. Also, the base 10 plates and selenium tablets may-be well counted out to the worker. Furthermore, the novel method involves a considerable saving of time since the selenium tablets are more ready to handle than is the selenium powder.

The novel method is illustrated by way of ex- 15 ample in the accompanying drawing, in which Fig. 1 shows one step thereof; Fig. 2 is a plan oi the arrangement represented in Fig. 1; Fig.3

manner serves as one electrode. On this plate selenium tablets 2 .are placed in the course of manufacture. These are. then spread out by means of a suitable tool in a manner to produce a selenium coating 2' on the plate I, as will be obvious from Fig. 3. Fitted to the coating 2' is the second electrode 3. I

What is claimed is: A method of producing selenium disks forrectlflers and photoelectric cells which comprises arranging selenium tablets on a base plate and spreading out these tablets to form a coating thereon.

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